Connecting to the Network

1. Connecting to the Network Networking for Home and Small Businesses – Chapter 3

2. Objectives • Explain the concept of networking and the benefits of networks. • Explain the concept of communication protocols. • Explain how communication occurs across a local Ethernet network. • Describe Access layer devices and communication methods on a local Ethernet network. • Describe Distribution layer devices and communication methods across networks. • Plan, implement, and verify a local network.

3. Networking and Its Benefits • Define the term network and identify various types of networks

4. Networks • Communication technology in the 1990s, and before, required separate, dedicated networks for voice, video and computer data communications. • Each of these networks required a different type of device in order to access the network. Telephones, televisions, and computers used specific technologies and different dedicated network structures, to communicate. • People can now watch live video broadcasts on their computers, make a telephone call over the Internet, or search the Internet using a television. Converged networks make this possible.

5. Network Benefits • Networks range from simple networks consisting of two computers, to networks connecting millions of devices. Networks installed in small offices, or homes and home offices, are referred to as SOHO networks. • These enable sharing of resources, such as printers, documents, pictures and music between a few local computers. • In business, large networks can be used to advertise and sell products, order supplies, and communicate with customers. • Networks allow for rapid communication such as email and instant messaging, and provide consolidation, storage, and access to information on network servers.

6. Networking and Its Benefits • Describe the benefits of computer networking and list examples of small, medium and large networks

7. Networking and Its Benefits • Business and SOHO networks usually provide a shared connection to the Internet. • The Internet is considered a "network of networks" because it is literally made up of thousands of networks that are connected to each other. • Here are other uses of a network and the Internet: • Sharing music and video files • Research and on-line learning • Chatting with friends • Planning vacations • Purchasing gifts and supplies

8. Networking and Its Benefits • Define the components of an Information network

9. Network components • There are many components that can be part of a network, for example personal computers, servers, networking devices, and cabling. • These components can be grouped into four main categories: • Hosts • Shared peripherals • Networking devices • Networking media

10. Network components • Hosts are devices that send and receive messages directly across the network. • Shared peripherals are not directly connected to the network, but instead are connected to hosts. • The network devices, as well as networking media, are used to interconnect hosts.

11. Networking and Its Benefits • Describe the Roles of computers on a network • Clients and servers

12. Roles of computers on a network • All computers connected to a network that participate directly in network communication are classified as hosts. • Hosts can send and receive messages on the network. In modern networks, computer hosts can act as a client, a server, or both. It’s the software installed on the computer that determines which role the computer plays. • Servers are hosts that have software installed that enable them to provide information, like email or web pages, to other hosts on the network. (A single computer can run multiple types of server software. ) • Clients are computer hosts that have software installed that enable them to request and display the information obtained from the server. (A single computer can also run multiple types of client software.)

13. Peer-to-Peer network • Client and server software usually runs on separate computers, but it is also possible for one computer to carry out both roles at the same time. • In small businesses and homes, many computers function as the servers and clients on the network. This type of network is called a peer-to-peer network. • The simplest peer-to-peer network consists of two directly connected computers using a wired or wireless connection. • Multiple PCs can also be connected to create a larger peer-to-peer network but this requires a network device, such as a hub, to interconnect the computers.

14. Networking and Its Benefits • Build computer peer-to-peer network and verify

15. Network Topologies • Differentiate between logical and physical topologies, and explain how networks are represented graphically

16. Network Topologies • Wired networks require lots of cabling and network devices to provide connectivity for all network hosts. • When networks are installed, a physical topology map is created to record where each host is located and how it is connected to the network. • The physical topology map also shows where the wiring is installed and the locations of the networking devices that connect the hosts. • In addition to the physical topology map, it is sometimes necessary to also have a logical view of the network topology. A logical topology map groups hosts by how they use the network, no matter where they are physically located.

17. Communication Protocols • Explain the concept of communication in terms of source, destination and channel

18. Communication Concept • The primary purpose of any network is to provide a method to communicate information. • All communication begins with a message, or information, that must be sent from one individual or device to another. • All communication methods have three elements in common. • The first of these elements is the message source, or sender. Message sources are people, or electronic devices, that need to communicate a message to other individuals or devices.

19. Communication Concept • The second element of communication is the destination, or receiver, of the message. The destination receives the message and interprets it. • A third element, called a channel, provides the pathway over which the message can travel from source to destination. • In any conversation between two people, there are many rules, or protocols, that the two must follow in order for the message to be successfully delivered and understood.

20. Communication Concept • Among the protocols for successful human communication are: • Identification of sender and receiver • Agreed-upon medium or channel (face-to-face, telephone, letter, photograph) • Appropriate communication mode (spoken, written, illustrated, interactive or one-way) • Common language • Grammar and sentence structure • Speed and timing of delivery

21. Communication Protocols • Explain the need for rules and protocols in order for communication to occur

22. Communication Protocols • Protocols are specific to the characteristics of the source, channel and destination of the message. • Protocols define the details of how the message is transmitted, and delivered. This includes issues of: • Message format • Message size • Timing • Encapsulation • Encoding • Standard message pattern

23. Communication Protocols • Explain the concept of encoding in relation to human communication

24. Message Encoding • One of the first steps to sending a message is encoding it. Written words, pictures, and spoken languages each use a unique set of codes, sounds, gestures, and/or symbols to represent the thoughts being shared. • Encoding is the process of converting thoughts into the language, symbols, or sounds, for transmission. • Decoding reverses this process in order to interpret the thought.

25. Message Encoding • Encoding also occurs in computer communication. Encoding between hosts must be in an appropriate form for the medium. • Messages sent across the network are first converted into bits by the sending host. Each bit is encoded into a pattern of sounds, light waves, or electrical impulses depending on the network media over which the bits are transmitted. • The destination host receives and decodes the signals in order to interpret the message.

26. Message Formatting • When a message is sent from source to destination, it must use a specific format or structure. • Message formats depend on the type of message and the channel that is used to deliver the message. • The process of placing one message format (the letter) inside another message format (the envelope) is called encapsulation. • De-encapsulation occurs when the process is reversed by the recipient and the letter is removed from the envelope.

27. Message Formatting • Each computer message is encapsulated in a specific format, called a frame, before it is sent over the network. • A frame acts like an envelope; it provides the address of the intended destination and the address of the source host.

28. Communication Protocols • Explain the concept of message formatting and encapsulation

29. Communication Protocols • Explain that messages have size restrictions depending on the channel used

30. Message size • An individual conversation may be made up of many smaller sentences to ensure that each part of the message is received and understood. • Likewise, when a long message is sent from one host to another over a network, it is necessary to break the message into smaller pieces. • The rules that govern the size of the pieces, or frames, communicated across the network are very strict. They can also be different, depending on the channel used. Frames that are too long or too short are not delivered.

31. Timing and Access methods • Explain the concept of timing and access methods in relation to human communication • Access Method • Access Method determines when someone is able to send a message. These timing rules are based on the environment. • Therefore , it is necessary for computers to define an access method. Hosts on a network need an access method to know when to begin sending messages and how to respond when errors occur.

32. Timing and Access methods • Flow Control • Timing also effects how much information can be sent and the speed that it can be delivered. • In network communication, a sending host can transmit messages at a faster rate than the destination host can receive and process. Source and destination hosts use flow control to negotiate correct timing for successful communication. • Response Timeout • Hosts on the network have rules that specify how long to wait for responses and what action to take if a response timeout occurs.

33. Communication Protocols • Explain standard message patterns in relation to human communication • Unicast • Multicast • Broadcast

34. Message Patterns • A one-to-one message pattern is referred to as a unicast, meaning that there is only a single destination for the message. • When a host needs to send messages using a one-to-many pattern, it is referred to as a multicast. Multicasting is the delivery of the same message to a group of host destinations simultaneously. • If all hosts on the network need to receive the message at the same time, a broadcast is used. Broadcasting represents a one-to-all message pattern. • Additionally, hosts have requirements for acknowledged versus unacknowledged messages.

35. Communication Protocols • Relate human communications concepts of messages, unit sizes, timing, encapsulation, encoding and standard message patterns to the term “protocol” .

36. Protocols and Importance • All communication, both human and computer, is governed by pre-established rules, or protocols. These protocols are determined by the characteristics of the source, channel and destination. • Protocols are especially important on a local network. In a wired environment, a local network is defined as an area where all hosts must "speak the same language" or in computer terms "share a common protocol".

37. Protocols and Importance • The most common set of protocols used on local wired networks is Ethernet. • The Ethernet protocol defines many aspects of communication over the local network, including: message format, message size, timing, encoding, and message patterns.

38. Importance of standardization • In the early days of networking, each vendor used their own, proprietary methods of interconnecting network devices and networking protocols. Equipment from one vendor could not communicate with equipment from another. • Standards are beneficial to networking in many ways: • Facilitate design • Simplify product development • Promote competition • Provide consistent interconnections • Facilitate training • Provide more vendor choices for customers

39. Protocols • There is no official local networking standard protocol, but over time, one technology, Ethernet, has become more common than the others. It has become a de facto standard. • The committee responsible for the Ethernet standards is 802.3. • Since the creation of Ethernet in 1973, standards have evolved for specifying faster and more flexible versions of the technology. This ability for Ethernet to improve over time is one of the main reasons that it has become so popular.

40. Communication Across a Local Ethernet Network • Physical addressing identifies Source, Destination and Channel on an Ethernet Network

41. Physical Addressing • All communication requires a way to identify the source and destination. • On Ethernet networks, a method exists for identifying source and destination hosts. Each host connected to an Ethernet network is assigned a physical address which serves to identify the host on the network. • Every Ethernet network interface has a physical address assigned to it when it is manufactured. This address is known as the Media Access Control (MAC) Address. The MAC address identifies each source and destination host on the network.

42. Communication Across a Local Ethernet Network • Describe some of the basic characteristics of Ethernet for communicating across the channel

43. Ethernet Communication • The Ethernet protocol standards define many aspects of network communication including frame format, frame size, timing and encoding. • When messages are sent between hosts on an Ethernet network, the hosts format the messages into the frame layout that is specified by the standards. • Frames are also referred to as Protocol Data Units (PDUs).

44. Ethernet Communication • The format for Ethernet frames specifies the location of the destination and source MAC addresses, and additional information including: • Preamble for sequencing and timing • Start of frame delimiter • Length and type of frame • Frame check sequence to detect transmission errors.

45. Communication Across a Local Ethernet Network • Describe the need for a hierarchical design in an Ethernet Network

46. Ethernet Network hierarchical design • On an Ethernet network, the host MAC address is similar to a person's name. • A MAC address indicates the individual identity of a specific host, but it does not indicate where on the network the host is located. • If all hosts on the Internet (over 400 million of them) were each identified by only their unique MAC address, imagine how difficult it would be to locate a single one.

47. Ethernet Network hierarchical design • Ethernet technology generates a large amount of broadcast traffic in order for hosts to communicate. • Broadcasts are sent to all hosts within a single network • Broadcasts consume bandwidth and slow network performance. Imagine what would happen if the millions of hosts attached to the Internet were all in one Ethernet network and were using broadcasts! • It is better to divide larger networks into smaller, more manageable pieces and one way to divide larger networks is to use a hierarchical design model.

48. Hierarchical design • Hierarchical design is used to group devices into multiple networks organized in a layered approach, this allows local traffic to remain local. Only traffic that is destined for other networks is moved to a higher layer. • It provides increased efficiency, optimization of function, and increased speed. • The hierarchical design has three basic layers: • Access Layer - to provide connections to hosts in a local Ethernet network. • Distribution Layer - to interconnect the smaller local networks. • Core Layer - a high-speed connection between distribution layer devices.

49. Communication Across a Local Ethernet Network • Explain the purpose of a logical network address as the location of a host on a Network (source and destination)

50. Logical addressing • With the hierarchical design, there is a need for a logical addressing scheme that can identify the location of a host. • This is the Internet Protocol (IP) addressing scheme. • On a host, the MAC address does not change; it is physically assigned to the host NIC and is known as the physical address. The physical address remains the same regardless of where the host is placed on the network. • The IP address is similar to the address of a person. It is known as a logical address because it is assigned logically based on where the host is located. The IP address, or network address, is assigned to each host by a network administrator based on the local network.